Injection molding hot runner nozzle with removable seal

Abstract

A flow nozzle ( 10 ) that conveys plastic melt from an injection unit of a molding machine to a mold cavity ( 72 ) has an improved, removable seal design. The nozzle body ( 12 ) is designed to threadedly receive a nozzle tip ( 24 ) that includes an outlet ( 30 ) that communicates with the mold cavity. A thin-wall, cylindrical seal ring ( 40 ) includes a compression portion that is received between the nozzle body and nozzle tip and is compressed to create a seal between these two elements when the tip is assembled to the nozzle body. The seal ring further includes a sealing portion ( 50 ) that encircles the nozzle tip and has an outer diameter slightly larger than the outer diameter of the nozzle body.

What is claimed is:  
     
       1. A flow nozzle ( 10 ) to convey plastic melt to a mold cavity ( 72 ), the flow nozzle ( 10 ) including a nozzle body ( 12 ) having a central passageway ( 18 ) that extends from a plastic melt inlet to an outlet ( 30 ), and a nozzle tip ( 24 ) threadedly received in the nozzle body ( 12 ), the nozzle tip ( 24 ) being configured to be received in a mold gate ( 70 ) and to include the outlet ( 30 ) that communicates with the mold cavity ( 72 ), characterized in that the flow nozzle ( 10 ) further comprises a thin-wall, cylindrical seal ring ( 40 ) having a compression portion ( 42 ) that is received between the nozzle body ( 12 ) and nozzle tip ( 24 ), such that the compression portion ( 42 ) of the seal ring ( 40 ) is compressed to create a seal between the nozzle body ( 12 ) and nozzle tip ( 24 ) when the tip is assembled to the nozzle body ( 12 ), the seal ring ( 40 ) also having an outer sealing portion ( 50 ) that encircles the nozzle tip ( 24 ). 
     
     
       2. A flow nozzle ( 10 ) in accordance with  claim 1  characterized in that the outer sealing portion ( 50 ) of the seal ring ( 40 ) has an outer diameter slightly larger than the outer diameter of the nozzle body ( 12 ). 
     
     
       3. A flow nozzle ( 10 ) in accordance with  claim 1  characterized in that the compression portion ( 42 ) of the seal ring ( 40 ) has a wall thickness in the range of 0.20 to 0.50 mm. 
     
     
       4. A flow nozzle ( 10 ) in accordance with  claim 1  characterized in that the compression portion ( 42 ) of the seal ring ( 40 ) is received within a recess ( 14 ) in the nozzle body ( 12 ). 
     
     
       5. A flow nozzle ( 10 ) in accordance with  claim 4  characterized in that the compression portion ( 42 ) of the seal ring ( 40 ) is trapped between a shoulder  16 ) in the recess ( 14 ) of the nozzle body ( 12 ) and a shoulder ( 44 ) extending radially outward from the nozzle tip ( 24 ). 
     
     
       6. A flow nozzle ( 10 ) in accordance with  claim 5  characterized in that the outer sealing portion ( 50 ) of the seal ring ( 40 ) extends below the shoulder ( 44 ) of the nozzle tip ( 24 ) and has an outer diameter slightly larger than the outer diameter of the nozzle body ( 12 ). 
     
     
       7. A flow nozzle ( 10 ) in accordance with  claim 6  characterized in that both the compression portion ( 42 ) and outer sealing portion ( 50 ) of the seal ring ( 40 ) have a wall thickness in the range of 0.20 to 0.50 mm.